Can I set my daughters phone in a way that there are only approved numbers she can text or call?

To create a pure whitelist of specific numbers that can call or be called, login into the Boomerang Web Management Dashboard and then click on the Child Device and the Calls Tab. Here, use the “Allow calls only to/from the following numbers” option and enter the number and click on the green + sign.

Texts:

In the fall of 2015, Google made changes to the Android operating system with the release of Android 5.x that no longer allows the blocking of text messages. So we can only notify Parents when certain numbers text your child and/or your child texts certain numbers. So there is no way to block text messages for certain numbers and allow them for certain numbers.

So we can block Calls but not Texts. We can only notify you when an unknown or blocked number texts or is texted. If you want to be sure that you get notifications when a number texts or is texted then add that number into the web management dashboard Texts Tab under “The following numbers text my child:”